The present invention relates to a lock adjustable or programmable to operate with different keys and to methods of providing and operating such a lock.
There are many instances in which it is desirable to change the keying of a lock. For example, when one loses a key to a lock, particularly a door lock, the primary concern is often not with unlocking the lock since duplicate keys are usually left with relatives, neighbors, landlords, superintendents, building agents, etc., but that the finder of the key will be able to identify the location of the lock and unlock it. That concern becomes more serious when the key was lost or stolen under circumstances which permit an identification of the key owner, such as when a woman's handbag is lost or stolen, or when a set of keys is taken, for example, from an automobile. In such instances, the lock must either be rekeyed or changed to prevent the lost or stolen key from operating the lock. In either case, a locksmith was usually called to change the keying of the lock or to replace the lock itself.
Pin tumbler locks which may be rekeyed without removing the tumblers, and therefore rekeyed without a locksmith, are known. U.S. Pat. No. 1,565,556 of Fremon, issued Dec. 15, 1925, and U.S. Pat. No. 2,603,081, of Pelle, issued July 15, 1952 disclose locks which must be removed from the lock assembly in which they have been assembled in order to effect rekeying. Therefore, while those locks may not require a locksmith for rekeying, rekeying would not ordinarily be attempted by someone who is not mechanically inclined.
The U.S. Pat. No. 1,565,556 to Fremon discloses a pin tumbler lock which is selectively operable with two keys. In one condition of the lock it is only operable with one of the two keys, and in another condition of the lock it is only operable with the other of the two keys. The lock includes an annular ring which encloses a lock plug having a keyway therein. Both the ring and the plug are rotatable relative to the lock casing. A pair of radially extending pins engage either the ring and plug together so that both rotate relative to the casing, or the ring to the casing so that only the plug rotates relative to the casing. A bar is movable to cause the pins to engage the ring and plug together or the ring to the casing. In order to change the condition of the lock, i.e., rekey it, the lock has to be removed from a lock assembly in which it is assembled to gain access to the movable bar so that its position may be changed.
Pelle U.S. Pat. No. 2,603,081 discloses a rekeyable lock in which the longitudinal position of one of the tumbler assemblies is changed by a gear assembly to rekey the lock. However, access to the gear assembly which repositions that tumbler assembly is obtained from the rear of the lock which requires that the lock be removed from a lock assembly in which it is installed.
A lock which may be rekeyed from the exterior thereof without removing it from a lock assembly in which it is assembled is disclosed in U.S. Pat. No. 3,257,831 of Schlage, issued June 28, 1966. The lock disclosed in U.S. Pat. No. 3,257,831 to Schlage is selectively operable with primary and secondary keys, initially only with the secondary key, and rekeyable by the primary key to operate with the primary key instead of the secondary key. The lock can not be rekeyed from the exterior of the lock by the secondary key to operate again with the secondary key, but may be rekeyed by the primary key to operate with the secondary key. Thus, the same key which is used to operate the lock also rekeys the lock. As a result, the functions of rekeying and operating the lock can not be separated so that anyone authorized to rekey the lock can also operate it. Rekeying is accomplished in the U.S. Pat. No. 3,257,831 to Schlage by reconfiguring the keyway to limit the distance that the secondary key may be inserted, thereby preventing the secondary key from properly positioning the tumblers for operation of the lock.
A lock which may be rekeyed from the exterior by a reset key which adjusts the positioning of the tumblers is disclosed, for example, in U.S. Pat. No. Re. 28,319 of Kerr, which was reissued on Jan. 28, 1975 (original patent issued on Sept. 4, 1973). U.S. Pat. No. Re. 28,319 to Kerr discloses an axial pin tumbler lock which includes a number of pin tumbler sets that extend circumferentially about the lock, each of the tumbler sets including three axially-extending tumblers. One set of circumferentially-extending tumblers is rotated relative to the other two sets by the reset key to form new combinations of three tumblers for each tumbler set, thereby rekeying the lock. The reset key must be inserted into the lock in the same angular position relative to the lock that it was in when it was last withdrawn from the lock, otherwise the lock can not be rekeyed. In order to facilitate proper introduction of the reset key, U.S. Pat. No. Re. 28,319 to Kerr suggests that the front of the lock be marked with indicia to indentify the positions of the axial tumbler sets. However, such indicia may distinguish the exterior appearance of the lock from a non-rekeyable lock of the same type and thereby suggest that the lock may be rekeyed.
A lock commercially available from U-Change Lock Industries, Inc. of Oklaholma City, OK is rekeyable from the exterior thereof by adjusting the positioning of the tumblers. In order to rekey the lock, both a change tool which repositions the pin-tumblers that operate the lock and a key with which the lock is to operate must be inserted into the lock. While the key is inserted in the keyway of the lock, a slot is provided at the exterior of the lock adjacent the keyway through which the change tool is inserted. The slot, however, distinguishes the exterior of the lock from conventional locks and may suggest that the lock is rekeyable.
A lock commercially available from Winfield Locks, Inc. of Costa Mesa, CA is rekeyable from the exterior thereof to operate with different master keys. The lock includes one keyway for the usual unlocking key and a second keyway for an emergency or master key. The lock is rekeyed to accept a new master key by inserting the current master key into the second keyway, turning it a quarter turn, and then inserting the new master key and turning it back the quarter turn. The presence of two keyways is evident and distinguishes the exterior of the lock from a conventional lock.
There is thus a need for a lock rekeyable from the exterior thereof, which appears from the exterior thereof to be a conventional lock, and which permits rekeying with the capability of preventing operation of the lock during rekeying and/or by the person rekeying.